AK2572 Datasheet, PDF (44/50 Pages) Asahi Kasei Microsystems – APC for Burst Mode Applicable Direct Modulation Laser Diode

ASAHI KASEI
[AK2572]
10. Operation Modes
The AK2572 has the following 3 operation modes － Self-Operation Mode where temperature compensation
operation is automatically executed in accordance with EEPROM setting, Adjustment Mode where each LD
adjustment is made and EEPROM Access Mode where adjusting data is written into EEPROM.
10.1 Self-Operation Mode
With the On-chip oscillator, those functions as temperature detection, read out of temperature compensation
data from EEPROM and LD drive current setting by APC control, are automatically executed. At the
Power-on, the AK2572 is put into Self-Operation Mode.
10.2 Adjustment Mode
This is a mode to adjust each LD characteristic. When the device is put into this mode, the temperature
compensation operation stops and various setting data can be written via Digital I/F. Adjustment is made by
accessing the internal Register via Digital I/F.
10.3 EEPROM Access Mode
This is a mode to write LD adjusting data and various set-up data into EEPROM.
10.4 Mode Control
In Figure 10-1, “Mode Transition Flow Chart” is shown. Transition to each mode is controlled by some
commands (Refer to Section 10.5) via Digital I/F. Access to Digital I/F is prohibited for 2 msec [Typ.] after the
transition to Self-Operation Mode is made (After the Power-on and after issuing Operation mode change
command). Accessible EEPROM / Register via Digital I/F in each operation mode is listed in Table 10-1.
Figure 10-1 Mode Transition Flow Chart
Power
ON
Hold data
in Register
Adjustment
Mode
Self-Operation
Mode
Start-up
Start-up
Shutdown
Shutdown
EEPROM
Access Mode
Table 10-1 Operational Conditions in Each Mode
WP-pin
R_WP_CTRL
[*1]
Operation mode
EEPROM
Read Write
Register
Read
Write
L
－
Fixed at Self-Operation Mode ○ [*2]
×
×
×
1
Fixed at Self-Operation Mode ○ [*2]
×
×
× [*1]
H
0 [*4]
Self-Operation Mode
Adjustment Mode
○
×
○
× [*1][*3][*5]
○
×
○
○ [*5] [*6]
EEPROM Access Mode
○
○
×
× [*5]
[*1] If WP-pin＝“H”, writing into R_PASSWD is always possible in Self-Operation Mode. When R_PASSWD
and E_PASSWD agree, writing into R_WP_CTRL becomes possible.
[*2] When Write Protect is enabled (WP-pin＝“L” or R_WP_CTRL＝“1”), Self-Operation Mode is set as the
operating mode and Read Only operation is possible at Device Address＝“A0h”.
[*3] When Write Protect is released, writing into R_PWR_SEL[1:0] at Address＝”A8h / 2Fh” in Self-Operation
Mode is possible. Power Leveling[2] is enabled at R_PWR_LVL1_SET＝”0”、R_PWR_LVL2_SET＝”1”.
[*4] Full access is possible when Write Protect is released (WP-pin＝”H” and R_WP_CTRL＝”0”).
[*5] “Operation Mode Change command “ can be executed.
[*6] In Adjustment Mode, when R_SFP_SET is modified, the access via Digital I/F cannot be made for 80 msec
[Typ.] from the data modification.
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< MS0290-E-01>
2004/8